Sodium Bicarbonate → HCID 70616087, compound

Participants

Reaction Steps

A suspension of t-butyl 7β-amino-3-vinylceph-3-em-4-carboxylate hydrogen p-toluenesulphonate (1.14 g. 2.5 mmole) in methylene chloride was shaken with a solution of sodium hydrogen carbonate (206 mg., 1 equiv.) in water (20 ml.) until the organic layer cleared. The aqueous phase was re-extracted with methylene chloride (20 ml.), and the combined organic phases were washed with water (20 ml.), and dried. The solution of t-butyl 7β-amino-3-vinylceph-3-em-4-carboxylate so obtained was stirred and treated with a solution of DL-dicyclohexylcarbodiimide (515 mg., 1 equiv.) in methylene chloride (20 ml.), followed by a solution of Dl-2-t-butoxycarbonylamino-2-(2-naphthyl) acetic acid (753 mg., 1.0 equiv.) in methylene chloride (20 ml.), previously warmed to achieve solution. The reaction mixture was stirred at 23° for 21/2 hours, and the precipitated N,N'-dicyclohexylurea was filtered off. The filtrate was washed with 3%-sodium hydrogen carbonate solution (30 ml.), water (20 ml.), 2N-hydrochloric acid (20 ml.), and water (20 ml.), dried and evaporated to a pale-yellow solid. This solid was triturated with ethyl acetate (160 ml.), the insoluble dicyclohexylurea was removed by filtration, and the filtrate was evaporated to give the title ester as a crystalline solid (1.26 g, 80%), λmax. 288 nm (E1cm 1% 283), λmax. (CHBr3) 3426 (NH), 1780 (azetidin-2-one), 1720 (CO2R), 1708 and 1500 (NH CO2R), 1694 (CONH) and 908 cm-1 (=CH2). The pmr spectrum of the product in CDCl3 showed it to be a 1:1-mixture of the two diastereoisomers (the new centre of asymmetry is in the side-chain attached to the 7-position). d. 7β-[DL-2-Amino-2(2-naphthyl)acetamido]-3-vinylceph-3-em-4-carboxylic Acid

Provenance & Evidence